The Bush administration wants Congress to thwart a plan to give thousands of federal crack cocaine offenders a chance to marginally reduce prison sentences that are a hundred times more severe than those meted out for powder cocaine offenses.

In a statement prepared for his scheduled appearance before the House Judiciary Committee today, Attorney General Michael B. Mukasey said that unless Congress acts, "1,600 convicted crack dealers, many of them violent gang members, will be eligible for immediate release into communities nationwide" under a decision by the U.S. Sentencing Commission.

"Retroactive application of these new lower guidelines will pose significant public safety risks . . ." Mukasey said in the statement. "Many of these offenders are among the most serious and violent offenders in the federal system and their early release . . . would produce tragic, but predictable results."

The commission, an independent body created by Congress to set parameters for people convicted of federal crimes, voted in December to retroactively apply more relaxed sentencing guidelines to current inmates. The action was aimed at offsetting a disparity between prison time meted out to those convicted of possession or sale of crack cocaine and the sentences given for powder cocaine crimes.

Nearly 20,000 inmates could be released over a span of seven to 10 years after the plan takes effect March 3. Mukasey wants Congress to act in about three weeks.

Under current law, possession of five grams of crack cocaine triggers the same mandatory minimum sentence as possession of 500 grams of powder cocaine. Because most crack cocaine offenders are black, and most powder cocaine offenders are white and Latino, civil rights activists, some lawmakers and scores of judges have said this disparity is discriminatory.

When the commission eased the guidelines in May, Congress had until November to prevent them from going into effect. It declined to do so. After that, the commission moved to apply the guidelines retroactively.

Supporters of the commission's action say the fears raised by Mukasey are overblown. They note that inmates would have their petitions to be released heard by judges who would consider filings from prosecutors and probation officers before determining an offender's fitness to reenter society.

"I'm really kind of shocked that Attorney General Mukasey would seemingly not have faith in the American judicial system to do all it can to ensure that violent offenders are not released early and to address a fundamental injustice in the criminal justice process," said U.S. District Judge Reggie B. Walton, who presides in the District. "His position presupposes that judges will be irresponsible in exercising their discretion."

The federal judiciary supported the Sentencing Commission, citing the law's harsh impact on first offenders. It was joined by federal public defenders, probation officers and activists.

Mukasey seemed to factor the criticism into his statement. "In calling for action, I emphasize that we are not asking this committee to prolong the sentences of those offenders who pose the least threat to their communities, such as first-time, non-violent offenders."

The controversy over the sentence-reduction plan made its way into the presidential campaign trail when it was brought up during a Dec. 1 debate between Democratic candidates.

Sen. Hillary Rodham Clinton (N.Y.) said she was against making the guidelines retroactive. "In principle, I have problems with retroactivity," she said. "It's something a lot of communities will be concerned about, as well."

Sen. Barack Obama (Ill.) wavered. "Even if we fix this, if it was a 1 to 1 ratio, it's still a problem that folks are selling crack. It's still a problem that our young men are in a situation where they believe the only recourse for them is the drug trade."